1. Field of the Invention
This invention relates to a sliding coupling between universal joints of a power shaft accommodating variations in axial spacings of the joints without loss of power transmission and sealing telescoped coupling components against ingress of dirt or egress of lubricant. Specifically, the invention deals with a universal or cardan joint having an internally splined hollow hub or boss portion, a second universal or Cardan joint on one end of a shaft having an externally splined pin on the other end slidable in the hub in non-rotatable relation with a tube carried by the pin surrounding the hub and having a plastics seal member riding on the hub to hold the tube in concentric relation therewith and having flexible sealing lips to retain lubricant and exclude dirt from the coupling. The hub may be coated with a low friction plastics material to facilitate sliding of the seal.
2. Prior Art
Seals for sliding couplings have heretofore accommodated radial displacement of telescope parts causing an imbalance of the seal bringing about excessive wear and friction. For example, in U.S. Pat. No. 3,633,383 issued Jan. 11, 1972 to the assignee of this application, radial movement between the splined shaft hub and the surrounding tube can occur on eccentric loading of the tube relative to the hub or on the application of bending forces on the tube. These bending forces or eccentric loads will cause elastic deformation of the tube so that the seal is heavily loaded in certain areas causing premature wear because of unequal load distribution and, of course, increasing the sliding friction